The present invention relates to a catalyst for polymerizing vinyl compounds and a process for producing vinyl polymers using the catalyst, and more particularly, to a catalyst for polymerizing vinyl compounds which is capable of efficiently producing vinyl polymers having terminal vinyl bonds, and a process for producing vinyl polymers using such a catalyst.
Metallocene catalysts (Kaminsky catalysts) used together with methylaluminoxane (MAO) as a co-catalyst have been found to be useful as catalysts for the polymerization of olefins, and have been extensively studied. However, in order to allow the metallocene catalysts to exhibit its catalytic activity, it is necessary to use therewith a large amount of the expensive methyl aluminoxane. To solve the problem, for example, Japanese Patent Application Laid-Open No. 5-25214 has proposed to use a methylalumoxane co-catalyst supported on clay minerals (one of silicon-containing layered compounds) as a catalyst component for olefin-polymerizing catalyst, and specifically describes a methylalumoxane co-catalyst supported on smectite (clay minerals are used as a catalyst support). However, the preparation of such a co-catalyst inevitably requires to treat clays with a large amount of expensive and harmful methylalumoxane, and the obtained catalyst is still insufficient in polymerization activity per unit quantity of the aluminum component used. In addition, U.S. Pat. No. 5,308,811, etc., have proposed the use of clays treated with an aluminum compound such as trialkylaluminum as a co-catalyst, and specifically describes a catalyst composition comprising a metallocene complex, clay minerals, etc. However, the catalyst composition fails to achieve a sufficient polymerization activity for vinyl compounds only by treating clays with ordinary organoaluminum compounds. WO 99/02472 describes a process for producing xcex1-olefins using a catalyst composed of a specific iron complex and an organoaluminum compound, and also describes the use of acidic clays such as montmorillonite as a support of activated catalysts or catalyst precursors. However, when methylaluminoxane described as a specific example of the organoaluminum compound is used as a catalyst component, the catalytic activity, especially the activity per unit quantity of aluminum, is still unsatisfactory.
Japanese Patent Application Laid-Open No. 8-295705 describes a process for producing xcex1-olefins by the oligomerization of ethylene, in which xcex1-olefins are separated from a reaction product to recover a catalyst and by-produced polymers. In this process, after separating xcex1-olefins by distillation using an evaporator, the by-produced polymer and catalyst are recovered in the concentrated liquid residue. Also, Japanese Patent Application Laid-Open No. 10-45833 describes a process in which a reaction product solution is kept at a high temperature in order to inhibit the precipitation of by-produced polymer and facilitate subsequent treatments. In these conventional processes, since xcex1-olefins are separated by distillation in the presence of the catalyst components, xcex1-olefins are susceptible to side reactions such as isomerization. Further, Japanese Patent Application Laid-Open No. 7-149671 describes a process in which after preliminarily separating by-produced polymer, an ethylene oligomer (xcex1-olefin) is separated and purified. In any of the prior art processes, ethylene is trimerized in the presence of a chromium catalyst to produce oligomers thereof. Further, these processes require an additional step for subjecting the catalyst components to deactivation or deashing treatment for removal thereof. In particular, in the process described in Japanese Patent Application Laid-Open No. 7-149671, since a homogeneous catalyst system comprising a chromium complex is used to enhance the catalytic activity, it is not possible to completely remove the catalyst components upon removal of the by-produced polymer. In addition, a pyrrole compound added to improve the activity of the chromium catalyst is difficult to remove, resulting in failure to purify xcex1-olefins having 8 or more carbon atoms.
A first object of the present invention is to provide a catalyst for the polymerization of vinyl compounds which is capable of efficiently producing vinyl polymers having terminal vinyl bonds. A second object of the present invention is to provide a process for producing vinyl polymers using the above catalyst. A third object of the present invention is to provide a catalyst for the production of xcex1-olefins which is readily separated from the reaction product after oligomerization reaction. A fourth object of the present invention is to provide a process for producing xcex1-olefins using the above catalyst for the production of xcex1-olefins in which the catalyst and by-produced polymer are readily separated from the reaction product.
As a result of the extensive studies for accomplishing the above objects, the inventors have found that vinyl polymers are efficiently produced in the presence of a catalyst comprising (A) a complex of Group 4 to 10 transition metal of the Periodic Table, (B) a clay, clay mineral or ion-exchangeable layered compound, and (C) a specific aluminoxy compound. The inventors have further found that xcex1-olefins are efficiently produced in the presence of a catalyst comprising (Axe2x80x2) a complex of Group 8 to 10 transition metal of the Periodic Table, (Bxe2x80x2) an organic compound-modified, clay, clay mineral or ion-exchangeable layered compound, and (Cxe2x80x2) a specific aluminoxy compound, and that the catalyst is readily separated from a reaction product. The present invention has been accomplished based on these findings.
Thus, the present invention provides a catalyst for polymerizing vinyl compounds comprising (A) a complex of Group 4 to 10 transition metal of the Periodic Table, (B) a clay, clay mineral or ion-exchangeable layered compound, and (C) at least one aluminoxy compound represented by the following general Formula (1): 
wherein a plurality of R groups are each independently a C1-10 hydrocarbon group, and at least one of the R groups is a hydrocarbon group having 2 or more carbon atoms; and x is an integer of 2 or more.
The process for producing vinyl polymers comprises a step of polymerizing at least one vinyl compound selected from the group consisting of olefins, styrene, styrene derivatives, acrylic acid derivatives and vinyl esters of fatty acids in the presence of the catalyst for polymerizing vinyl compounds as defined above.
The present invention further provides a catalyst for producing xcex1-olefins comprising (Axe2x80x2) a complex of Group 8 to 10 transition metal of the Periodic Table, (Bxe2x80x2) an organic compound-modified, clay, clay mineral or ion-exchangeable layered compound, and (Cxe2x80x2) at least one aluminoxy compound represented by the following general Formula (2): 
wherein a plurality of R groups are each independently a C1-10 hydrocarbon group, and at least one of the R groups is a hydrocarbon group having 2 or more carbon atoms; and y is an integer of 2 to 4.
The process for producing xcex1-olefins comprises a step of oligomerizing ethylene in the presence of the catalyst for producing xcex1-olefins as defined above.